docs: def digest(self, method, node):
          """
          Returns the digest of an object from a method name
          :param method: hash method
          :type method: str
          :param node: Object to hash
          :type node: str
          :return: hash result
          """
          if method not in constants.TransformUsageDigestMethod:
              raise Exception('Method not allowed')
          lib = hashlib.new(constants.TransformUsageDigestMethod[method])
          lib.update(node)
          return base64.b64encode(lib.digest())